Blasting assembly



Aug. 29, 1939. YOUNG 2,171,384

BLASTING ASSEMBLY Filed Nov. 4, 1937 2 Sheets-Sheet 1 fig. 2

'Fr'ed yQq /g' INVENTOR.

q BY Wm- Wieawn A TTORNEY Aug. 29, 1939. a F. mum;

BLASTING ASSEMBLY Fill-3d Nov. 4, 1937 2 Sheets-Sheet 2 free? youngmmvroa.

A TTORNEY Patented Aug. 29, 1939 2,171,384 'Bmscrmo ASSELY Fred Young,West Haven, Conn, assignor to E. I.

du Pont de Nemours & Company, Wilmington, lDeL, a corporation ofDelaware Application November 4, 1937, Serial No. 172,699

6 Claims.

This invention relates to a new and improved blasting assemblyparticularly adapted for use with explosives which are incapable ofdetonation by means of the more commonly known 6 initiators.

The recent introduction into practical use of these relativelyinsensitive explosives, as disclosed by Kirst and Woodbury in U. S. P.1,992,217, necessitates the employment of a booster charge 10 of highvelocity explosive more sensitive than the main charge. The additionofsaid booster charge has, in turn, required modification ofthe blastingassemblies heretofore known to the explosives art. I

1 The object of my invention is an improved blasting assembly capable ofinitiating a main charge of explosive not sensitive to the action of acommercial blasting cap. A further object is a blasting assembly whichis completely moistureproof. A still further object is a blastingassembly whereby loading in the bore-hole is facilitated. Additionalobjects will be disclosed as the invention is herein described.

I have found .that the foregoing objects are accomplished by the use ofa blasting assembly comprising a rigid moistureproof receptaclecontaining at least one solid detonating explosive composition capableof initiation by a commercial blasting cap or Cordeau fuse. receptacleis provided with external means for holding an initiator parallel to thelongitudinal axis 'of the explosive charge, said means being adjacentthereto and in propagating relationship therewith.

Preferably, the rigid receptacle is made of tin-coated steel or similarmaterial which permits a facile assembly that is moistureproof. Althoughthe receptacle may be madein any desired form, I prefer the cylindricalshape because of the convenience it affords at the place of application.The means for holding the initiator in the desired position may beconstructed of the same material as the receptacle and likewise mayassume any form. I have found it desirable to use a dJ-shaped length ofmaterial because the legs of the U may be aflixed readily to the wallsof the receptacle to form a tunnel-shaped holder. The wall thickness ofthe initiator holder should be such that the wall is sufiiciently strongto withstand the crushing action encountered in the loading and tampingof the bore-hole. When tin-coated steel is employed, I have found a wallthickness of 0.022 inch to be satisfactory, although an appreciablevariation may be made therefrom if loading conditions be varied. TheU-shaped holder, when attached to the outer wall of the receptacle,forms a tunnel having a cross-section which permits the insertion of theinitiator, pordeau fuse for example, said tunnel extending in adirection parallel to the longitudinal axis of the main explosive chargeso that the initiatoris held adjacent to and in propagating relationshipwith said explosive charge.

The assembly is particularly adapted for use with those detonatingexplosives which are insensitive to the action of Cordeau or a com=mercial blasting cap, as well as to those that do not performsatisfactorily when initiated thereby. An example of such insensitiveexplosive is one comprising 92%; ammonium nitrate, 4%

dinitrotoluene, and 4% paraifin at a density not less than 1.0. Such acomposition may comprise the main charge of my blasting assembly. As a.booster charge, I prefer touse trinitrotoluene, although any soliddetonating explosive that is sensitive to theaction of a blasting capmay be employed; for example, tetryl, pentaerythrite tetranitrate,picric acid, various dynamites, and many others. These materials areused in amounts-capable of detonating the main explosive charge. Thebooster charge may be in actual contact with the insensitive main chargebut I prefer to keep it separate, although, of course, in propagatingrelationship therewith.

It should be understood that it is more desirable in some operations tolocate the primer con taining the booster charge of trinitrotoluene orthe like in some position in the column of explosive away from the endsof said column. For.

instance, the primer receptacle containing the booster charge may belocated near the center of a column of receptacles containing charges ofthe principal explosive. The body of the booster charge oftrinitrotoluene or the like may in turn be located in the center of theprimer receptacle, the ends of which may be filled with the principalexplosive. The tube for the initiator will, of course, be locatedoutside of the container, and at least a portion of said tube willextend adjacent to said booster charge. Accordingly, if the boostercharge of trinitrotoluene or the like is located in the center of acontainer or column, the explosive wavewill be initiated at that pointand travel in two, directions towards each end of said container orcolumn of explosive.

To illustrate'the invention more clearly, reference is made to. theaccompanyingdrawings. Fig. 1 is a. vertical view of my blastingassembly. Fig.

.of the receptacle.

2 is a view in cross-section, while Fig. 3 is a plan view of the same.

Fig. 4 is a view in cross-section depicting the booster located withinthe charge. Fig. 5 is a similar view depicting the booster locatedwithin the column of a'plurality of charged receptacles. Similarnumerals refer to similar parts throughout the drawings.

Referring to Fig. 1, the numeral l designates a cylindrical rigidmoistureproof receptacle. The means for holding the initiator parallelto the longitudinal axis of the explosive charge is shown at 2. Thecross-section of this holder is shown more clearly in Fig. 3, saidcross-section being of such size that the Cordeau fuse 3 may passtherethrough. Although the initiator holder, as shown, extends only ashort distance along the yvall of the receptacle, it may, in certaincases, be desirable to extend said holder over the entire length. Theupper end of the Cordeau fuse (not shown) extends beyond the bore-holeso that a blasting cap or other initiator may be attached thereto, whilethe lower end is retained in position by means of a tube 4, which iscrimped about the fuse 3. The tube 4 may be made of gilding metal,copper, or similar material and is provided with projections at the basein order that the string 6 may' be conveniently fastened thereto, theother end of said string being tied to the loop I,- which is firmlyattached to the base The ball 5 aifords a means for lowering theblasting assembly.

Fig. 2 shows the cap-insensitive main charge at 9 with the boostercharge comprising trinitrotoluene or similar material 8 adjacent theretobut separated therefrom by the disc Hi. In this figure the Cordeaufuse-extends downward only a short distance beyond the booster chargethereby necessitating a change in the position of tube 4. This is doneby increasing the length of the string 6. It will be noted that theinitiator holder extends substantially over the entire depth of thebooster charge, but over only a small portion of the main charge.However, the length of the initiator may be varied according to theparticular explosive charges employed, in order that'the desired resultsmay be obtained. Likewise, the booster charge may, if desired, belocated in the center rather than at the top of the container.

The Fig. 4 depicts the, booster charge 8 located near the center of thecap-insensitive main charge 9,'whiie the tube 2, disposed outside thelateral Wall of the receptacle I, is shown as adapted to receive andhold a continuous detonating fuse 3, adjacent to and in propagatingrelationship with said booster charge 8.

Fig. 5 depicts the booster charge 8 located at the end of one chargedreceptacle but within a column formed by two of said charged, re-

ceptacles.

The modus operandi comprises lowering the blasting assembly into thebore-hole by means of the bail, the upper end of the Cordeau fuseremaining above the surfaces so that it is accessible for initiation bymeans of a blasting cap or similar device. Once initiated, the Cordeaufuse attains a high velocity of detonation, which employed therewith,the containers filled with the Kirst explosives are loaded into theborehole. The blasting assembly is then lowered and centered on the topcontainer, and initiation of the charge is eflected in the usual manner.Likewise, the assembly shown herein has a high practical value in theso-called deck loading, 1. e. when the explosive charge is spaced atintervals in the bore-hole. In this case, it will be desirable to usetwo blasting assemblies, placing one at a lower level in the bore-hole,so that it is in propagating relationship with. one of the explosivecharges, while the second assembly is placed in propagating relationshipwith the uppermost explosive charge, said assemblies beinginterconnected by a Cordeau fuse, said Cordeau fuse runningsubstantially the depth of the bore-hole. When employed in this manner,very satisfactory performances result, while failures to detonate arereduced to a minimum. Moreover, the blasting assembly shown herein ismoistureproof so that the danger of the explosive charge becominginsensitive, due to the absorption of moisture, is obviated.

The blasting assembly herein disclosed possesses many characteristicsthat make its application advantageous. It will be understood, however,that many variations may be made from the details set forth withoutdeparting from the spirit and scope of the invention. For example, forcertain combinations of booster and main explosive charge, it may bedesirable to employ one or more blasting caps in place of the Cordeaufuse. been mentioned throughout, I do not wish to be limited thereto;for example, Primacord or the like, may be employed instead of Cordeaufuse as desired. I wish to be limited, thereto, only by the followingclaims.

I claim:

1. A blasting assembly comprising a substantially cylindrical watertightmetal container, 9. charge of detonating explosive within said containercomprisinga main charge incapable of detonation by means of a blastingcap and a booster charge including trinitrotoluene, and a metal tubesecured on the outside of the lateral wall of said container andapproximatelyparallel with the longitudinal axis thereof for confining adetonating fuse in propagating relationship with said booster charge.

2. A blasting assembly comprising a substantially cylindrical watertightmetal container, a booster charge comprising trinitrotoluene in saidcontainer, a metal tube permanently secured on the outside of thelateral wall of said container and approximately parallel with thelongitudinal axis thereof for confining a detonating fuse in propagatingrelationship with said booster charge. I

3. A blasting assembly comprising a substantially cylindrical watertightmetal container, a relatively insensitive explosive charge within eachend of said container, a 'boostercharge of trinitrotoluen'e disposedbetween -:.-.sa.id insensitive charges therein, and a metal tubepermanentlyv secured on the outsideof thelateral wall of saidFurthermore, although Cordeau fuse has container for confining adetonating fuse in propagating relationship with said booster charge.

4. A blasting assembly comprising a substantially cylindrical watertightmetal container, 9. charge-of detonating explosive within said containercomprising a main charge incapableofdetonation by means of a blastingcap and a booster charge sensitive to the action of a blastfor confininga continuous detonating fuse paring cap and capable of initiating saidmain charge, and a metal tube permanently disposed on the outside of thelateral wall of said container at a locus adjacent to said boostercharge for confining a continuous detonating fuse parallel to thelongitudinal axis of said explosive charge and in propagatingrelationship with said booster charge.

5. A blasting assembly comprising a substantially cylindrical watertightmetal container, a charge of detonating explosive within said containercomprising a main charge incapable of detonation by means of a blastingcap and a booster charge sensitive to the action of a blasting cap andcapable of initiating said main charge, and a metal tube permanentlydisposed on the outside of the lateral wall of said con-' tainer at alocus adjacent to said booster charge allel to the longitudinal axis ofsaid explosive charge and in propagating relationship with said boostercharge and anchoring means located on the outside of said container nearone extremity thereof for aligning said detonating fuse.

6. A blasting assembly comprising a substantially cylindrical watertightmetal container, a booster charge in said container comprising adetonating explosive sensitive to the action of a blasting cap andhaving a sensitiveness of the same order of magnitude astrinitrotoluene, a

metal tube permanently secured on the outside of the lateral wall ofsaid container and approximately parallel with the longitudinal axisthereof for confining a detonating fuse in propagating relationshipwith-said booster charge.

FRED YOUNG.

